Process of crystallizing sugar-juices.



P. KESTNER &' P. LAGRANGE. PROCESS OF GRYSTALLIZING SUGAR JUIGES.

APPLICATION FILED 00114, 1908.

Patented July 2, 1912.

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EN @TATEFa 'iEA iTENT Ph L KESTNER, 6F LII-(LE7 AND PROSPER LAGRANGE, 0F ?ARIS, FRANCE;

PROCESS QF CBYSTALLIZING SUGAR-JUICES.

Epecificationof Letters Patent.

Patented July 2, 1912,

Application filed October 14, 1908. Serial No. 457,735.

To all whom it may concern:

Beit known that we, PAUL Kizs'rxnn and Pnosri-zu LAGRANGE, citizens of the Republic of France, and residents of Lille, Department Nor-d, and Paris, France, respectively, have invented an Improved Process of Crystallizing Suqarduices, of which the following is a specincation.

Our invention relates to the manufacture of sugar and the object of our invention is to so evaporate the sugar syrup as to-increase the yield of the crystallizable content as lirst sugar, thereby avoiding the large percentage, of second and third crystalformat-ion common under the present methods of manufacturing sugar.

In the accompanying drawings, Figures 1 and 2 are diagrammatic views illustrating apparatus capable of carrying our improved process into eiiect. it has been proposed to increase the yield ott'lirst crystals by gradual cooling and agitation, such action taking place in a closed vessel under atmospheric pressure or in the open air. An improved method for obtaining massecuite has been employed in France in which evaporation to saturation' and subsequent crystallization are carried out in two distinct and separate operations in two separate apparati. Under this process, the syrup at 28 or 30 1%., just after it leaves the triple or multiple effect is drawn into the apparatus which is ordinarily used for boiling to grain. Evaporation in vacuum is carried to the pointof string proof ithoutforming grains, and then finally, under pressure, a high degree oi saturation is obtained Without, however, reaching the final state of saturation in Which the massecuitedoes not contain more than 5% of water; and then, to augment the saturation Without being obliged to evaporate still higher and thereby increase the temperature, some crystallized sugar is dissolved in the syrup thus concentrate-d. The Whole mass of saturated syrup thus obtained is allowed to crystallize a crystallizer by progressive cooling, which may be more or less rapid. By this method an increased amount of a rich and regular grain obtained with an case that cannot secured by crystallization a tested simultaneously evaporation in the pan (cuite). 1e process just described, however, pre two inconveniences which we desireto boiling temperature of about 120 to 122 Q. It has also been thought, up to the present time, that excessive heat altered the syrup, and all operators heretofore have attempted to concentrate at low temperatures. We have found, however, that this alteration of syrup is much'slower than was previously supposed; that in reality sugar juices can be evaporated at atmospheric pressure nearly to complete saturation when their boiling temperature is more than 120 8 centigrade Without any apparent inversion of sugar and no appreciable coloration, providing the operation is not too long continued.

Our usual e-vaporators in use at the present time, notably those of the film climbing type having elongated tubes constructed in accordance with the designs of Paul Kestn'er, of

Lille. France, such for instance as that forin- 9o ing the subject of" his British Patent Yo.

' 6,372, March 19, 1903. In recent operations of this evaporator We have discovered that sugar uices Were much less sensitive to heat than was usually supposed, and We have beenable to concentrate them at very hi h temperatures, a condition due to their rapid circulation in this apparatus, and the question of circulation coupled With high temperature-seems to be the secret of the results We have obtained.

in an evaporator such as described, we have concentrated a thin juice at a temperature of 128 (1, and have been unable to discover any alteration by analysis. We

have been proved, by trials on concentrated syrups, that the conditions are the same as above, and We believe that We can use a still higher temperature without risk.

Under such conditions we have been able to realize a new process which may be dedescribed as follows: in this process, the

ork has been carried on With the g5 I structure 1 represents an up and down cur-v rent evaporatorof the type shown in the sugar juice ust as it comes from the existing multiple eflect evaporators, or if the work is in a refinery, the uice as -1t'1s, generally sent to the boiling to grain pan is delivered to an evaporator which works at atmospher c pressure 'and'not ln-a vacuum. It

is possible to use the existing pans in sugar.

factories if they have a. heating surface sufficiently large to permit rapid evaporas tion, unless it should be necessary to give too high a pressure to the heating'surface. But we prefer to employ an evaporator in.

which concentration is made at a singlecontain only 5 per cent of water, and in refineries this would be even less.

.In Fig. 1 of "the accompanying drawings we have shown diagrammatically appara-. tus available for use in carrying out one part of our improved process. In this Kestner patent before referred to in which tubes are arranged for the ascent and de-' scent of the sugar juice or syrup received from the multiple effect. This juice enters from a pipe '2 under the influence of a pump 3 and steam enters the casing of the evaporator at the point 1. The juice asit comes from the multiple eflect evaporator 1s concentrated in the evaporator 1 in one pas sage. The steam pressure in the shell is from 3 to 3% atmospheres, and we regulate the feed into the evaporator in such away that the syrup leaves the evaporator with only about 5% water. 'The boiling temperature of this syrup-is between 125 and 128 C. The entering-juice or syrup is of a density equaling 30 Be. or higher, and after passing up and down within the elongated tubes of the evaporator it is discharged at 5 into the separator 6 at a temperature of from 115 to 125 Centigrade. The accompanying vapor escapes at 7 and the concentrated syrup or juice enters the crystal.- lizer 8 where its entering temperature is substantially maintained until this receptacle is filled. The vessel receiving the hot concentrated juice is provided with a cooling and stirring arrangement and when filled the mass is allowed to cool. Crystallization starts at about 110 O. or 115 C. It is difiicult to ascertain the exact point, but the choling is gradual and progressiveaccording to the desired size of the grain: slower I cooling producing large grains. and from the crystallizer the crystallized mass passes to the centrifugal 9 forthe usual treatment.

When great crystals are required we propose to substitute for the open crystallizer a closed crystall-izcr under vacuum, and in 2, we have shown diagrammatically such apparatus. The concentrated syrup delivered from the evaporator will be drawn- ;into the crystallize'r 8 consisting preferably of a llOl'lZOIltftl cylinder with anagitator.

lVhen-this is fullthe crystallizer will be connect'e'd by means of a v'alve10 with some condenser and will be put under a vacuum which at first will be only very small, and

which will increase slowly and. regularly. Thus the'temperaturewill be lowered regularly through the whole mass which is not.

possible with surface cooling with such a thick and non-conducting'mass. From the crystallizer, the mass will pass to'a conveyer 11, through a valved outlet 12, and thence to the centrifugal for thefusual treatment.

By not forcing th'ejconcentration too high: it IS posslble, particularly in refineries, to

make more concentrations and to make 5110- cessive crys'tallizations.

Concentration can be carried out in a mill tiple effect, and as amatter of fact in a double elfect. In this case the direction of travel of the. juice'in the pans would pref:

erably be counter-current that is to'say, thepan heated by direct steamwould receive the partially concentrated juicedehvered by the pan receiving the initial juice and heated by steam from the other pan. -We may note a still greater advantage of this process, in that the vapors given off by evaporation from the surface are utilizable', sometimes in the preliminary evaporating. apparatus, and sometimes in other heaters." Besides it is possible, without any inconvenience, to

give a slight counter-pressureto the evapo rat-or in order to be able more easily to,uti-

lize this vapor, and the boiling temperature 'rnay'thus be lncreased by several degrees.

We have proved that evaporating in a single pass as is done in the Kestner evaporator referred to there is not the slightest altera tion in the sugar juice.

' We'wish to afiirm a last advantage in this I Y process, in that it permits the preliminary multiple effectconcentration to be carried heretofore. Under the usual working conditions it is customary to send the juice to the boiling to grain pan when itreaches aevaporating the juice to a density of from 28 to 30 Baum under suitable temperaizc .to a higher point than has been possible i ture conditions, then rapidly circulating such ]ll1Ce m an evaporator under a temperature of from 125 to 130 (1, and up-= Ward until it is a substantially saturated solution, separating therefrom the vapor accompanying such saturated solution, maintaining such body of saturated solution in this condition and subjecting the same to agitation and during agitation gradually lowering the temperature of the mass to the point of crystallization, continuing the cooling of the entire mass for the formation of grain, and finally separating the crystal lized and uncrystallized portions of the solution.

2. The process of obtaining crystallized sugar from sugar juices, WhlCll comprises evaporating the same-to a density of from 28 to 30 Baum under suitable temperature conditions, then rapidly circulating such juice in a transit evaporator under a temperature of from 125 to C.,-- and" upward until it is a substantially saturated solution, separating therefrom the Vapor accompanying such saturated solution, maintaining such body of saturated solution in this condition and subjecting the same to agitation and during agitation gradually lowering the temperature of the mass to the point of crystallization, continuing the cooling of the entire mass in 'vacuo for the formation of grain and continuing agitation and finally separating the crystallized and uncrystallized portions of the solution.

In testimony whereof, we have signed our names to this specification in the presence 0 two subscribing witnesses. 3

PAUL KESTNER. PROSPER LAGRANGE.

Witnesses: A

HENRI CHARRIER, J. BELorr.

Copies of this patent may be obtained for five cents each,

by addressing the Commissioner of Patents.

Washington, D. 0. 

